The figure of this month's MUSSELp Mussel of the Month is from Spix & Wagner's 19th century treatment of the freshwater Mollusca of Brazil. They actually favored two different names for the shell illustrated above: Unio caudatus and Diplodon furcatum! This potential confusion, however, is moot since the same species was described earlier by Schumacher under the name Prisodon obliquus.